Office chair



FIG. 1 is a perspective view of an office chair showing my new design;

FIG. 2 is a top plan view thereof;

FIG. 3 is a front view thereof;

FIG. 4 is a first end view thereof;

FIG. 5 is a second opposite end view thereof; and,

FIG. 6 is a rear view thereof. 

The ornamental design for an office chair, as shown and described. 